Hydraulic hammers are used on work sites to break up large hard objects before such objects can be moved away. Hydraulic hammers may be mounted to back hoes or excavators, or may be hand-held. Typically, the hammer assembly is powered by either a hydraulic or pneumatic pressure source. During a work or power stroke, high fluid pressure is applied to a first shoulder of a piston, thereby driving the piston in a forward direction. The piston then strikes a work tool, which is driven in the forward direction thereby causing a work tip of the work tool to strike the rock, concrete, asphalt or other hard object to be broken up. During a return stroke, fluid pressure is applied to a second shoulder of the piston in order to return the piston to its original position.
The work tool is retained within a sleeve, commonly referred to as a front head. Conventionally a tool retention pin is used to retain the work tool within the front head. The pin extends across one side of the front head and engages with a transverse machined groove in the work tool. The height of the groove is greater than the diameter of the pin, thereby allowing reciprocal forward and backward movement of the hammer over a limited range of movement. The pin and groove are subject to burring in use, because of the repeated impact. Upon servicing it is necessary to remove the pin before the tool can be removed from the front head. The burring must then be removed before the pin or tool can be replaced in the front head. Moreover, the tool is restrained from rotation by the pin, so unwanted torque can be transferred from the tool to the tool assembly and the machine to which it is mounted.
At least some of the disclosed embodiments may overcome one or more of the abovementioned drawbacks.